Doug McCrae
Legend
If your adventures feature only one or two combat encounters you may never have seen the 15 min day. I ran more typical multi-encounter dungeons and saw it a heck of a lot. In fact in an underwater dungeon, where the party druid was expending a huge number of his slots on environment specific buffs, the party retreated after ONE fight. I've also experienced PCs literally running from encounter to encounter in several campaigns to get as much use as possible out of the min/level buffs. 3.x is all about the buffs. If you're buffed you win, if you're not you lose.
Now you may say the DM ought to send a revenge squad after the party if they 'cheat' by going to bed early. Often this isn't possible. Many dungeons, tombs and the like, don't have intelligent defenders. Or the monsters may be unable to track, very few have the Track feat after all. Or the PCs may employ magical means to make tracking impossible such as rope trick or dimension door. And from level 9 onwards they can just teleport back to town anyway.
Now you may say the DM ought to send a revenge squad after the party if they 'cheat' by going to bed early. Often this isn't possible. Many dungeons, tombs and the like, don't have intelligent defenders. Or the monsters may be unable to track, very few have the Track feat after all. Or the PCs may employ magical means to make tracking impossible such as rope trick or dimension door. And from level 9 onwards they can just teleport back to town anyway.